Hi Pilou, what you show there works but it's kind of a different design than the original one, you've left more space around each cell and you have more of a flat area between them. The part that's difficult about the original one is having not much space between the cells and having the cells kind of melt into one another rather than being separated.

If you modify your example by moving the cells close to each other such that there isn't enough room for a fillet to fit, then you'll have a lot of difficulty.

- Michael